Combustion-powered fastener-driving tools are of course well known in the art. One example of such combustion-powered fastener driving tools is disclosed within U.S. Pat. No. Re. 32,452 which issued to Nikolich on Jul. 7, 1987. In order to achieve acceptable or desirable tool firing and fastener-driving cyclical operational rates, relatively large air intake and combustion product exhaust port and valve structures have been structurally and operationally incorporated within such fastener-driving tools as a result of the use or employment of longitudinally or axially sliding combustion chamber structures or sections. It can readily be appreciated, however, that as a result of such sliding combustion chamber structure, auxiliary cooling structure or devices cannot be readily incorporated upon or operatively associated with the combustion chamber. In addition, as a result of the longitudinally or axially sliding movements of such combustion chamber components, the opening and closing of the air inlet and combustion product exhaust ports and valves is directly dependent upon the axial or longitudinal movements or strokes of the sliding combustion chamber structure. Accordingly, it has been experienced that the operational cycles of such conventional combustion-powered fastener-driving tools are slower than conventional pneumatically-powered fastener-driving tools. Still further, it is also noted that in typically conventional PRIOR ART fastener-driving tools, such as, for example, that disclosed within Nikolich, that the fuel is injected into the combustion chamber at only a single location. This structural arrangement militates against the rapid uniform distribution and combustion of the fuel within and throughout the combustion chamber.
In addition, a fan is often incorporated within the upper region of the combustion chamber for any one of several reasons, such as, for example, facilitating or assisting the mixture of the air and fuel components being injected into the combustion chamber prior to ignition, providing a turbulent atmosphere within the combustion chamber in order to in fact promote the rapid burning of the air-fuel mixture within the combustion chamber once ignition has been initiated, scavenging of the combustion exhaust products by means of fresh air being induced into the combustion chamber subsequent to the combustion and power stroke phases of the fastener-driving tool, and cooling of the tool. However, it is not always ideal to dispose a fan at within the upper axial region of the combustion chamber in view of, for example, the thermal environment, the presence of pressure or shock forces to which the fan is normally subjected over extended operational periods, and the like. Accordingly, relatively small and low-mass fans are normally required to be used, as well as relatively sophisticated mounting systems for the fans in order to permit the same to withstand the aforenoted pressure or shock forces attendant each combustion cycle. It might therefore be desirable to relocate the fan to an alternate position, such as, for example, external to the combustion chamber, however, this then becomes problematic in that alternate means or modes of operation must be provided in order to achieve the mixing of the air and fuel components within the combustion chamber prior to the initiation of an ignition cycle, the development of turbulent conditions within the combustion chamber in order to facilitate the rapid burning of the air-fuel mixture with-in the combustion chamber, the induction of fresh air into the combustion chamber in order to achieve scavenging of the combustion exhaust products out from the combustion chamber subsequent to the combustion and power stroke phases of the fastener-driving tool, and the cooling of the tool.
A need therefore exists in the art for a new and improved combustion-powered fastener-driving tool wherein the intake and exhaust valve structure is effectively simplified so as to permit the intake and exhaust valve structure to be opened and closed in a rapid manner such that the cyclic operations of the combustion-powered fastener-driving tool can be comparable to those characteristic of conventional pneumatically-operated fastener-driving tools. A need also exists in the art for a new and improved combustion-powered fastener-driving tool wherein the cooling of the tool, the distribution and mixing of the air and fuel components within the combustion chamber of the tool just prior to the ignition and combustion of the air-fuel mixture within the combustion chamber, and the scavenging of the combustion exhaust products out from the combustion chamber can be achieved by means supplemental to, or in lieu of, the disposition or presence of a rotary fan within the upper region of the combustion chamber. Furthermore, a need exists in the art for a new and improved combustion-powered fastener-driving tool wherein the fuel can be uniformly introduced into, and distributed throughout, the tool combustion chamber so as to effectively accelerate the combustion of the same and the attainment of the peak combustion pressure within the combustion chamber during the power operational phase or stroke of the tool.